Page 223 - CITS - Fitter Trade Pactical - Volume - 2

FITTER - CITS

Job Sequence

TASK 1 : Oxy - acetylene hand cutting straight and bevel cut
• Wear all safety clothing.
• Set the gas welding plant with a cutting blowpipe, and cutting oxygen regulator.
• Fit the correct cutting nozzle according to the thickness of the metal to be cut (for M.S. plate 10mm thickness
use 1.2mm dia. orifice cutting nozzle)
• Adjust both oxygen and acetylene gas pressure according to the cutting nozzle size. (Oxygen 1.6 kgf/sq.cm
and acetylene 0.15 kgf/sq.cm)
While adjusting the pressure keep the cutting blow pipe walls open
• Check the size of the raw material
• Mark and file to size 200x150x10
• Clean the plate from dirt, oil, grease paint, water etc.
• Mark gas cutting lines as per drawing.
• Punch witness marks on cutting lines
• Set the job on cutting table.
• Set the neutral flame.
• Wear the gas welding goggles.
• Hold the blowpipe at an angle of 900 between the line of cut and the cutting nozzle axis is between the nozzle
and the surface of the plate.
• Heat one end of the punched line up to cherry red hot condition.
• Keep the distance between the workpiece and the tip of the nozzle about 5mm.
• Place the preheat cone approximate 1.6mm above the plate.
• Move the flame in circle a little larger than the tip size. When metal is heated to Cherry red, move the tip to the
edge of the plate.
• Operate the cutting oxygen lever immediately and move the torch slowly along cutting direction.
• Maintain correct torch speed and distance between the plate surface and the nozzle up to the end of the cut.
• If long plates are to be cut, to get a good straight gas cut surface, clamp a straight edged flat parallel to the
line of cut and use a spade guide attached to the cutting torch. Move the torch uniformly along the clamped flat
and pressing the spade guide against the flat.
• On completion of the cut release the cutting oxygen lever and shut off the flame.

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CITS : C G & M - Fitter - Exercise 54